Bleached bran and bran products and methods of preparation

ABSTRACT

A method of bleaching bran, comprising treating bran with a hydrogen peroxide solution to produce lightened bran having fewer native flavor components is disclosed. In one embodiment, a bleached bran product suitable for admixing with whole wheat flour to produce white whole wheat flour having an “L” value on the Hunter scale of at least about 75 is disclosed. In one embodiment, cleaned bran is treated with a solution of chelating agents to remove or inactivate transition metals. Thereafter, exposure to oxidant substances, such as hydrogen peroxide, ozone, and so forth, in the presence of an alkaline compound produces bleached bran, which can be washed and dried for use in products such as flours, pastas, and so forth.

RELATED APPLICATION

[0001] The present application is a divisional of U.S. patentapplication Ser. No. 09/663,914, filed Sep. 18, 2000, which isincorporated herein by reference.

FIELD

[0002] The present invention relates to bleached grains and inparticular to bleached brans.

BACKGROUND

[0003] Whole grain products are known to be rich in dietary fiber andother nutrients. Although there are many health benefits associated withthe consumption of whole grain products, many consumers avoid suchproducts due to the relatively poor taste and color associated withwhole wheat flours. This is especially true of children, who can beparticularly selective in food choices.

[0004] Attempts to overcome these problems include use of ground-upwhite wheat rather than red wheat in an attempt to mask or reduce thebitter taste of the bran. However, the flour produced with these methodsstill has a bitter flavor and yields a baked product with a dark color.

[0005] It is generally believed that the presence of bran is a majorcause of the taste and color problems associated with whole wheatflours. Bran contains phenolic compounds, which may be responsible forthe bitter and astringent taste. Certain phenolic compounds, such astannins, can impart a brown or even grayish color to flour, particularlyflours made from red wheat. Thus, conventional processes used to producenon-whole wheat or white products attempt to remove as much bran aspossible during milling, although this is also removing a keynutritional component of the kernel. Specifically, bran not onlycontains fiber, but other healthy components that are known to be usefulin preventing cancer, such as colon cancer.

[0006] Thus, there is a continuing need for whole wheat flours that canbe used to provide finished whole wheat products that look and taste asgood as those made with “regular” white flour. Also, there is acontinuing need for bran products that are useful for addition toregular white or patent flour for the purpose of providing whole grainflours that are comparable to patent or white flours in taste,appearance and baking qualities, notwithstanding the presence of addedbran in the flours.

SUMMARY

[0007] A method of bleaching bran, comprising treating bran with ahydrogen peroxide (H₂O₂) solution to produce lightened bran having fewernative flavor components is disclosed. In one embodiment, a bleachedbran product suitable for admixing with wheat flour to produce whitewhole wheat flour having an “L” value on the Hunter scale of at leastabout 75 is disclosed.

[0008] The present invention provides a chemical lightening treatment orwetting process, or wet bleaching process that bleaches the bran portionof wheat kernels after cleaning and milling to produce a bleached branwithout the bitter aftertaste normally associated with whole grainproducts. This is unlike conventional white grain processes that seekremoval of bran in order to provide a product without a bitter taste.Bleaching only the bran portion of the wheat instead of the entirekernel also eliminates any potentially negative effects on flourfunctionality caused by bleaching an intact kernel.

[0009] In one embodiment, the present invention provides an intermediatebleached bran product. In another embodiment, a white whole grain flourhaving a high fiber content (10 to 12%) and other nutritional advantagesof a whole grain flour that nonetheless has a white color and blandflavor comparable to conventional white flour is provided. The whitewhole grain flour comprises a conventional flour and fortifying amountsof the intermediate bleached bran product.

[0010] In one embodiment, cleaned bran is treated with a solution ofchelating agents to remove or inactivate transition metals. This isfollowed by a blanching or heat treatment step to inactivate indigenouscatalase enzymes. Thereafter, exposure to oxidant substances, such ashydrogen peroxide, ozone, and so forth, in the presence of an alkalinecompound produces bleached bran, which can be washed and dried for usein products such as flours, pastas, cereals, cereal bars, functionalfoods, and so forth.

[0011] In a specific embodiment, bran is heated with a 600 PPM EDTAsolution at a temperature of about 70 to 90° C. for about five (5)minutes and then washed with deionized water. About 18 ml of about 30%hydrogen peroxide is added for every 50 grams of bran. A sufficientamount of sodium hydroxide is added to raise the pH to about 9-9.5 sothat the hydrogen peroxide can bleach the bran. In one embodiment, theblanched bran is bleached at about 122° C. at a pressure of about 103.4kilopascal (kPA) or one (1) atm (i.e., about 15 psi) for approximatelytwo (2) minutes. In another variation, the blanched bran is processed atatmospheric pressure at about 80° C. for about 40 to 60 minutes. Theresulting product is washed thoroughly with water and then filtered. Thebleached wet bran is then dried, such as in a rotating drum, at about276 kPA (40 psi). The final product still contains a sufficient amountof water so as to be utilized in any number of end products, such asflours, pasta, and so forth.

[0012] Flours comprising this bran exhibit minimal or no enzymeactivity, such as polyphenoloxidase and lipoxygenase activity, whichhelps to increase flour stability, particularly as it relates torancidity during storage. Another benefit is the white appearance ofcomposite flours utilizing the bleached bran, as the “L” value on theHunter scale can be in excess of 90. The water absorption of thebleached bran is also increased by up to six times in comparison tounbleached bran, which provides baking advantages known in the art. Theantioxidant activity in the bleached bran is also increased by at least15 to 20%, up to 30-35% or more, as compared with unbleached bran, whichis thought to have significant health benefits.

[0013] These and other features, aspects and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The FIGURE is a flow diagram showing a process for bleaching branin one embodiment of the present invention.

DETAILED DESCRIPTION OF INVENTION

[0015] In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which is shown byway of illustration, specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized. It is also to beunderstood that mechanical, procedural and system changes may be madewithout departing from the spirit and scope of the present invention.The following detailed description is, therefore, not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims and their equivalents.

[0016] Bleached bran, bran products, improved flours fortified with thebran products herein and methods of preparation are disclosed. A briefbackground on wheat and milling is given first, followed by adescription of various methods of producing bleached bran as well as adescription of the resulting bleached bran and bran products.

[0017] Wheat and Milling Background

[0018] The principle species of wheat are Triticum aestivum or breadwheat; T. durum which has extra hard kernels used primarily for macaroniand related pasta products; and T. compactum or club wheat, which hasvery soft kernels. Numerous varieties and cultivars within each speciesare known.

[0019] In the United States, wheat is classified according to whether itis hard or soft, white or red, and winter or spring. As a result thereare eight possible designations including: hard white spring, hard redspring, hard white winter, hard red winter, soft white spring, soft redspring, soft white winter, and soft red winter.

[0020] The white or red designation refers to the color of the wheatkernel. Currently, red wheat is more readily available in the UnitedStates than white wheat. As noted above, red wheat has a distinctivetaste due to the presence of high levels of catechin and catechintannins in the bran.

[0021] The hard or soft designation refers to protein strength andcontent of the wheat kernel. Tannin content is also known to be lower insoft wheat than hard wheat.

[0022] The winter or spring designation refers to the growth habitat ofthe wheat. Winter wheat is planted in the fall and harvested in thespring, whereas spring wheat is planted in the spring and harvestedlater that same crop year.

[0023] Wheat comprises a major starchy endosperm, a smaller germ orsprouting section of the seed and a surrounding bran or husk layer. The“endosperm” is the portion typically referred to, upon milling, as“flour” and generally makes up about 81-85% of the wheat kernel. Branmakes up about 11-15% of the kernel, with about one (1) to 3.5% beingthe germ portion. Bran with or without the germ is sometimes referred toas “mill feed.” Mill feed is a low value commodity typically used foranimal feed.

[0024] Wheat milling is a mechanical method of breaking open the wheatkernel to remove as much endosperm as possible from the bran and togrind or reduce the endosperm into flour. The process substantiallyseparates the major components of the wheat. Conventional whole wheatflour is produced by grounding “sound” wheat, i.e., wheat that issubstantially free of disease or other defects, other than durum. Theproportion of natural constituents, other than moisture, remain similarto the intact wheat kernel. Conventional white flour is produced whenmost of the bran is also separated from the endosperm. The germ fractionis usually separated from the rest of the kernel because its fat contentlimits the shelf life of the flour. However, some special purpose wholegrain flours include not only the bran but also the germ fraction. Theyield of flour or endosperm from milling is typically about 70-80%, withthe remaining endosperm still present in the bran.

[0025] The bran portion can vary considerably in starch and fibercontent. “Light” bran contains 10 to 20% starch and has a fiber contentof about 38 to 48%. “Heavy” bran contains more than 20%, up to 30%starch, and has a fiber content of between about 25 to 35%. “Native”bran refers to non-treated bran, i.e., bran that has not been subjectedto any chemical or physical treatment that may affect its dietary fibercontent.

[0026] Wheat color is measured using a colorimeter that uses either theCIE system or the triestimulus Hunter system. The Hunter value “L”denotes lightness; the “a” value denotes redness or greenness and the“b” value yellowness or blueness. A perfect white in the triestimulusscale has the following values: L=100, a=0 and b=0. Light bran obtainedfrom winter soft wheat has an approximate triestimulus value range ofL=70-74, a=4-5 and b=18-22. The latter parameters depend on crop year,location and growing conditions. Further discussion of the various typesof wheats is found in the Application entitled, “Bleached Grain andGrain Products and Methods of Preparation,” Ser. No. 09/392,699, filedSep. 9, 2000, commonly assigned, which is hereby incorporated byreference in its entirety.

[0027] Flour milling is a low margin commodity operation. As a result,even small increases in the extraction or mill feed ingredients candramatically and disproportionately affect the profitability of amilling operation.

[0028] Bleached Bran Processes

[0029] The starting material can be any type of wheat, although a whiterfinal product is obtained with a whiter starting material, such as awhite wheat. For this reason, white wheat brain is the preferredstarting material. In one embodiment, a soft white wheat is used as thestarting material. In another embodiment, red wheat is used as thestarting material. The wheat is cleaned and milled in any suitablemanner known in the art to produce wheat bran. In one embodiment,“light” bran from winter soft white wheat is produced and used in theprocess. As noted above, milling does not completely separate thecomponents. As a result, the wheat bran can contain wheat germ inamounts up to about 20 percent or more, and the starchy endospermcontent can be about 15 to 30%, depending on type. Generally, higheramounts of starch require more reagents for removal, thus increasingcosts.

[0030] The bran can be any suitable particle size, such as 100 micronsor more. Although bran with a smaller particle size can be used, thereis a tendency towards clumping during the process when the bran particlesize is less than about 100 microns. In one embodiment, the bran isground prior to the bleaching process to produce a ground bran having aparticle size ranging from about one (1) to 40 microns. In anotherembodiment, the bran is ground during or at the end of the bleachingprocess. In yet another embodiment, the bran is not further ground aftermilling.

[0031] In the embodiment shown in the FIGURE, the bran-bleaching process100 begins when unbleached bran 101 is treated 102 with a chelatingagent in order to substantially inactivate or remove transition metalspresent in the bran. Such metals include, but are not limited to,manganese, copper and iron. This is important because active transitionmetals can decompose bleaching agents, such as hydrogen peroxide. Sincemilling is a commodity process, small increases in the efficiency ofperoxide utilization are important to obtaining commercially practicalmethods.

[0032] The chelating agent needs to be present for a sufficient time andat a sufficiently high temperature in order to minimize the effect ofthe transition metals. In one embodiment, the chelating process isrelatively rapid, taking only about one (1) to 15 minutes at atemperature of about 70 to 90° C. In another embodiment, the processtakes less than about one (1) minute. In yet another embodiment, theprocess takes between about one (1) to two (2) minutes to complete at atemperature of about 80° C.

[0033] Any suitable type of transition metal sequestering components,i.e., chelating agents, can be used. This includes, but is not limitedto, any orthophosphate, metaphosphate, pyrophosphate (e.g., tetra sodiumpyrophosphate), polyphosphate, 1,2, diaminoethane,ethylenediaminetetraacedic acid (EDTA), and so forth. The EDTA can be inthe form of calcium EDTA or sodium EDTA. With the exception of EDTA, thechelating agent can be present in any suitable concentration, such asbetween about one (1) to two (2)%. Generally, higher concentrations ofchelating agents remove more metals, although the upper level isgenerally limited by good manufacturing practices. However, sinceend-product levels of EDTA are mandated by the U.S. government, EDTA istypically added at much lower concentrations, such as between about 0.02to 0.1% (200 to 1000 PPM) in solution with water.

[0034] In one embodiment, the mixture of bran and chelating agentsolution contains about 30% solids and about 70% liquids, by weight. Ina specific embodiment, about 45.4 kg (100 lbs) of bran is mixed atambient temperature with a liquid solution of 0.06% EDTA weighing about106 kg (233 lbs).

[0035] The treated bran is then washed and rinsed in a first washing andrinsing step 104 as shown in the FIGURE. In this step, water is used topartially rinse away the chelate transition metal that has combined withthe chelating agent. Preferably, the water is soft water with low levelsof iron (less than about five (5) PPM), manganese (less than about 0.02PPM) and copper (less than about 0.02 PPM). (Soft water is generallydefined as water having less than about two (2) grains of hardness(calcium and magnesium) per gallon). In one embodiment, distilled ordeionized water is used. Washing can be accomplished with a suitableamount of agitation. Rinsing can also be accomplished by any suitablemeans, such as with a combination of agitation and spraying. Theresulting washed bran is filtered or dewatered in a first filtering step106 by any suitable means, such as with centrifugation mechanicalpressing or low-pressure extrusion. The water (waste or recycle) stream108 containing the chelating agent can be recycled for use again in theprocess or discarded, as desired. In one embodiment, there is no firstwashing and rinsing step 104 or first filtration step 106, althoughempirically, it is believed that washing also serves to remove some ofthe soluble bitter-flavor components.

[0036] The washed bran is then blanched or heat-treated in a blanchingstep 110 to inactivate indigenous catalase and peroxidase enzymaticsystems (known as hydroperoxidases) that can otherwise detrimentallyaffect the activity of the hydrogen peroxide by decomposing it intohydrogen and oxygen, which can cause foaming. Peroxidase is a heatstable indicator enzyme, i.e., once the peroxidase is inactivated, mostother enzymes have also been inactivated. In one embodiment, theblanching step 108 is performed at a temperature of about 75 to 85° C.for three (3) to ten (10) minutes, although the invention is not solimited.

[0037] Residual catalase enzymatic activity can be measured by anysuitable method. In one embodiment, a qualitative method is used inwhich a small amount of hydrogen peroxide solution is added and a visualdetermination is made as to the formation of bubbles. The presence ofbubbles indicate that oxygen is being evolved, i.e., peroxidedecomposition. If no bubbles are present, the process proceeds to thebleaching step 118 described below.

[0038] In one embodiment, about 99% of the enzyme activity is destroyedin the blanching step 110. In another embodiment, residual enzymeactivity is below about ten (10) CIU/g bran (catalase internationalunits). CIU refers to the amount of enzyme in grams that catalyses thedecomposition of one (1) micromole of hydrogen peroxide per minute.

[0039] The washed and blanched bran is then washed in a second washingand rinsing step 112 as shown in the FIGURE, which can be followed by asecond filtering step 114 that has an associated waste or recyclingstream 116. Preferably, water having a low metal content is used for thesecond washing and rinsing step 112. In one embodiment, soft water, asdescribed above, is used. These steps, 114 and 116, also help to reducethe transition metals that still may be present. In one embodiment thereis no second washing and rinsing step 112 or second filtering step 114,although again, it is thought that by providing one or more washing,rinsing and filtering steps at some point in the process, an addedbenefit can be achieved, i.e., removal of certain undesirable solublebitter flavor components.

[0040] At this point, between about 40 to 60% of the manganese, about50% of the copper, and about 10 to 20% of the iron have been removed orinactivated. In another embodiment, more than 60% of the manganese, morethan 50% of the copper, more than 20% of the iron, as well as amounts ofother transition metals, have been removed or inactivated. In a specificembodiment, the resulting material has less than about six (6) PPMcopper, less than about one (1) PPM of manganese, and less than aboutten (10) PPM of iron. As a consequence of the washing steps 104 and 112,starch is also removed. In one embodiment, the amount of starch isreduced after two washing steps from about 19-20% to less than aboutthree (3)%, by weight.

[0041] The FIGURE further indicates that the present process 100 alsoessentially comprises a step 118 of bleaching the washed and blanchedbran. In the bleaching step 118, the wet bran is treated with an oxidantsubstance, such as hydrogen peroxide, ozone, and/or peracetic acid inthe presence of heat. In one embodiment, concentrated hydrogen peroxide,such as about six (6) to 40% hydrogen peroxide, is added to the wetbran. Since concentrated peroxide is less stable at elevatedtemperatures, it is preferably stored as cold liquid at a temperature ofabout −25 to 5° C. and then added to the bran at a temperature no higherthan room temperature to avoid increased spontaneous decomposition. Moredilute peroxide can also be used, although such a process is lessefficient.

[0042] The amount of oxidant employed depends upon a variety ofprocessing parameters and desired level of bleaching. In order to keepcosts down, the minimum amount required to accomplish the desired levelof bleaching is generally used. In one embodiment, about one (1) to 20parts of hydrogen peroxide to about 100 parts of bran (dry basis) isused. In preferred embodiments, the peroxide utilization rates rangefrom about 1 to 5 parts of hydrogen peroxide per 100 parts bran.

[0043] Since the pH of hydrogen peroxide is about 6 to 6.7, it does notreact readily with the bran. As a result, it is necessary to add analkaline substance, such as sodium hydroxide, potassium hydroxide oralkaline salts, i.e., sodium carbonate or polyphosphates, i.e.,trisodium phosphate, to increase the initial pH for the bleachingreaction to about 9 to 9.5 (at room temperature). The alkaline solutioncan have a concentration in excess of about one (1)% up to about ten(10)% or more. In one embodiment, an aqueous alkaline solution is addedin amounts of about 10 to 15 parts (dry weight) of alkaline material per100 parts bran. In one embodiment, the bran is treated with the alkalineand oxidant solution simultaneously. In another embodiment, thesolutions are added sequentially. In yet another embodiment, no alkalinesolution is added. Further optimization of the process can be achievedby measuring pH changes throughout the bleaching process. In this way,pH values can be corrected based on known dependence of pH ontemperature.

[0044] The bleaching step 118 is carried out at elevated temperatures.In one embodiment, the bran is bleached by “heating” it with aconcentrated hydrogen peroxide solution, together with sodium hydroxideat atmospheric pressure and a temperature of between about 80-90° C. forabout 20 to 60 minutes. In another embodiment, the bleached bran issubjected to a high-pressure treatment at a pressure of about 83 to 124kPA (12 to 18 psi) for about one (1) to five (5) minutes at atemperature of 120-130° C. In a specific embodiment, the bran isbleached for about two minutes at a pressure of approximately 103.4 kPA(15 psi) and temperature of about 122° C. However, operating the processat elevated pressure requires a special pressurized vessel with suitablerelief valves to avoid build-up of excess pressure. In one embodiment,about three (3) to 10% pure hydrogen peroxide per 100 g of dry gram ofdry bran is used. In a specific embodiment, a mixture of about 10%peroxide solution and one (1)% alkaline solution is heated together withthe bran to about 85° C. for about four (4) to five (5) minutes underatmospheric conditions. Use of peroxide in the bleaching process isadvantageous in that it degrades into harmless oxygen and water. Incontrast, other types of bleaching techniques such as those that employchlorine or benzoyl peroxide, can result in either undesirablemodification of the functional properties of a finished flour in whichthe bleached bran is used or undesirably high concentrations of residualbleaching agents or both.

[0045] The peroxide can be sprayed onto the bran or the bran can besoaked in a heated bath of peroxide. In one embodiment, a peroxidestabilizing agent, such as about one (1)% sodium silicate and/ormagnesium sulfate (about 0.1%) is used.

[0046] The bleached mixture can then be subjected to a third washing andrinsing step 124, followed by a third filtering step 126 with itsassociated waste or recycling stream 128 shown in FIG. 1. Any suitabletype of water can be used to wash and rinse the bran, such as “soft”water as described above. These latter steps remove most of the oxidant,although some residual oxidant does remain. For example, if 10% hydrogenperoxide is used, the residual after bleaching can be as high as two (2)to three (3) percent. By providing a washing and rinsing step 124followed by a filtering step 126 at this point in the process, it ispossible to reduce the concentration of hydrogen peroxide to less thanabout 0.5%. It may be possible to omit the step of washing, rinsing andfiltering the bleached bran in those embodiments where residual hydrogenperoxide is relatively low, such as less than about one (1)% by weight.However, higher residual concentrations of hydrogen peroxide can resultin foaming, which can cause a number of problems, such as, overflow inthe system, development of excessively-high pressure, and so forth.Providing at least one washing step is generally recommended in theprocess of the present invention, as it appears to provide the sidebenefit of removing certain soluble bitter flavor components.

[0047] The resulting bleached bran product is treated 130 with asuitable amount of catalase in order to destroy any remaining oxidant,such as the hydrogen peroxide. In one embodiment, a commercialpreparation of catalase, such as the one obtained from the fungiAspergillus nigers, is used. In a particular embodiment, between about0.1 and 0.4% of catalase, by weight, of bran, is added at an operatingtemperature of about 55 to 65° C. In one embodiment, the operatingtemperature is about 60° C. In this step, the oxidizing compound can bereduced to less than about five (5) PPM such that the bleached bran issubstantially free of hydrogen peroxide.

[0048] The catalased bran can be dried 132 at this point or firsttreated with ozone 134 as shown in the FIGURE. Treatment with ozonefurther whitens the bran, and offers a low cost option to further treatthe bleached bran, if desired. However, in most instances, the bran isbleached sufficiently for use in most desired applications. In oneembodiment, whiteness of the bleached bran is improved by treating thebran with 0.1% to two (2)% ozone, by weight, at pH 4-5. In thisembodiment, ozone is generated in an ozone generator and the bran istreated in an enclosed system or vessel that keeps the ozone and thelow-pH bran in intimate contact. The consistency of the bran can varyfrom about 20 to 40%, depending on water retention. Mixing of the ozoneand bran can be accomplished by any means known in the art, such as bymechanical means (e.g., tumbling device, rotary device with mixingblades, etc). In one embodiment, the reaction of ozone and bran is inthe range of about 90 to 95%, e.g., for about 100 g of incoming ozone,only about ten (10) g of ozone exits the reaction vessel or system.

[0049] Any suitable type of drying method can be used, such as highpressure drying, air drying, freeze drying and so forth. The finalproduct, i.e., (dried) bleached bran 134, is preferably driedsufficiently so that there are about five (5) to 13 grams of water per100 grams of dry bran. In one embodiment, the bran is ground from aparticle size of about 500 microns to a particle size of less than about100 microns, such as about 40 to 50 microns. For embodiments in whichEDTA has been used as the chelating agent, the residual EDTA level inthe bleached bran is less than about 100 PPM, and may be much lower. Inone embodiment, the treated bran has a pH of between about six (6) andseven (7), such as about 6.7.

[0050] By treating the bran and germ separately from the rest of thewheat kernel as described herein, an increase in flour functionality,particularly baking functionality, is obtained at a reduced cost.Further, since gluten-forming proteins are not present in the bran, thebleaching process can occur at higher temperatures as compared with thewhole kernel bleaching as described in application Ser. No. 09/392,699,noted above. This is advantageous as bleaching action is facilitated byheat, although temperatures in excess of 85 to 90° C. are generally notused since competing reactions, such as browning can begin to occur athigher temperatures.

[0051] In an alternative embodiment, many of the corresponding processsteps as described in Application (Ser. No. 09/392,699), can be appliedto clean bran, with modifications where appropriate, due to thedifferences between utilizing bran versus whole kernels.

[0052] Those skilled in the art will recognize that the equipment usedin the above-described process can be any conventional equipmenttypically utilized for the particular steps. In one embodiment, a drumdryer operating at about 207 to 345 kPA (30 to 50 psi), such as about276 kPA (40 psi), is used in the drying step 132. Drum drying provides aquick and economic method for drying the bran.

[0053] In another embodiment an extruder is used for the bleaching andcatalase addition steps, 118 and 130, respectively, together with anadditional cool-down step. The third washing and rinsing step 124 aswell as the third filtering step 126 is performed outside of theextruder in this embodiment. Use of an extruder allows the process to berun in a continuous manner rather than as a batch process. Further,there is more control over temperature and pressure, since excess steamcan easily be vacuumed off.

[0054] Bleached Bran and Bleached Bran Products

[0055] The resulting bleached bran can vary from a light red to a yellowcolor, but is visibly lighter than untreated or unbleached bran. Thefinal bran color is controlled by a combination of factors, including,but not limited to, the proportion of oxidant in the suspension,processing temperature, pH of suspension, processing pressure andprocessing time. For example, if the pH and temperature are too high,too much browning may occur. High temperatures may also promote thedevelopment of off-flavors. However, if the temperature is too low, theefficiency of the bleaching process decreases. Use of increased amountsof oxidant produces a whiter product, but increases the costs as well.There is also typically an optimum amount of time for the bleaching step(118) to operate, depending on the pressure conditions as noted above.Exceeding this time can be detrimental to the dietary fiber content ofthe end product.

[0056] Unbleached bran made from white wheat typically has an L value onthe Hunter scale of about 72 to 73. The bleached bran of the presentinvention has a higher L value than unbleached native bran. In oneembodiment, the L value is greater than about 75. In another embodiment,the L value of the bleached bran is between about 82 and 93. In aparticular embodiment, about five (5)% bleached bran, by weight, havingan L value of about 84 is added to an all-purpose whole wheat flourhaving an L value of about 93.3. The resulting composite flour in thisinstance has an L value of about 92.4. In other embodiments, thecomposite flour can have an L value of between about 82 and 93.

[0057] In comparison, a typical whole wheat flour produced byconventional methods that contains native or unbleached bran can have anL value of about 80 to 84. In one embodiment, flour combined with“drum-dried” bleached bran produced according to one of the processes ofthe present invention has an L value of about 85.2. In anotherembodiment, flour combined with “freeze-dried” bleached bran producedaccording to one of the processes of the present invention has an Lvalue of about 92.5. This compares favorably with typical all-purposewhite flour, which has an L value of about 93.

[0058] It should be noted that typical white flour is usually “bleached”using a combination of chlorine, benzoyl peroxide and/orazodicarbonamide. These oxidants exert their action by oxidizing thecarotenoid pigments that give the yellow color to flour. However,conventional bleaching processes do not easily oxidize the components inbran that are responsible for the brown coloring, e.g., such as ligninand other polyphenols. As such, oxidants such as chlorine, benzylperoxide and azodicarbonamide would not be suitable oxidants in theprocesses of this invention. Furthermore, chlorine bleached white flouris undesirable in many countries and not used. As a result, most bakedgoods outside the United States do not have as light a texture, i.e.,they are much denser. Ongoing attempts to improve functionality in theseproducts include use of unbleached white flour, heat-treated whiteflour, bleached white flour and/or mixtures thereof.

[0059] In addition, the anti-oxidant activity of the bleached bran isincreased significantly by the alkaline treatment with hydrogenperoxide. Specifically, the bran contains an aleurone layer that isrelatively high in phenolic compounds, including ferulic acid. While notwishing to be bound by the proposed theory, it is speculated herein thatbleaching with oxidants at a high pH, i.e., in excess of about 9, causesthe lignin portion of the cell wall to degrade. This degradation causesthe ferulic acid (which may be present in reduced amounts as comparedwith native bran) to become more available, i.e., the anti-oxidantactivity is increased. In one embodiment, the antioxidant activity inthe bleached bran is increased by at least 15 to 20%, up to 30-35% ormore, as compared with unbleached bran, depending on bleachingconditions. This increase in activity occurs even though otherantioxidant components, such as vanillic acids and certain otherphenolic acids, such as caffeic acid, are oxidized and no longeravailable. The increase in activity of the ferulic acid, however, issufficient to offset this loss, causing the net increase in anti-oxidantactivity as noted above.

[0060] The increased anti-oxidant activity carries over into the blendedproduct, i.e., such as a composite flour. The activity does decreaseover time, depending on storage conditions, such as temperature, etc.However, any increased antioxidant activity may have a beneficial ormodulating effect on consumer health. Some medical studies suggest thatwhole wheat flour may have a modulating effect in preventing certainhealth conditions such as colon cancer.

[0061] The water absorption of the bleached bran is also improved, as itis increased by up to six times in comparison to unbleached bran.Specifically, the bleaching treatment removes part of thelignocellulosic and hemicellulose material of the cell walls. As aresult, the cell wall structure is disrupted with a concomitant increasein the water holding capacity of the treated material. Increased waterabsorption in the bran improves water absorption in any composite flourusing the bran, which provides increased consistency and predictabilityin baked goods, as well as increasing yield. When added to regular orwhite flour, the whole wheat or bleached bran enriched flour alsobeneficially exhibits improvements in water absorption. Such increasedwater absorption of the flour is a great benefit in baking applicationsinvolving variations in water addition due to equipment or operatorerror.

[0062] The moisture content of the bleached bran, on a “fresh” or “asis” basis, is between about four (4) to 12%. On a dry basis, the rangeis about 4.2 to 13.6%.

[0063] The resulting bran also has an improved taste as compared withuntreated bran. The improvement in taste is significant enough to benoticeable by most consumers. In one embodiment, a consumer panel rateda bread product containing bleached bran made according to the presentinvention, i.e., a “white” whole wheat product, at least 50% improved intaste as compared with conventional whole wheat bread. This tasteimprovement is likely because the flavor components, including phenoliccompounds, such as caffeic acid, tannins, coumaric acid, and so forth,as well as other polyphenolic compounds have been sufficiently removedor modified so as to reduce the associated bitter tastes to acceptablelevels. By using the bleaching processes of the present invention, thebitter flavor components present in the native bran are reduced,although the precise percentage of reduction associated with thenoticeable flavor improvement has not yet been determined.

[0064] Although the use of bleached bran may have some detrimentaleffects on dough mixing and stability characteristics as compared withunbleached bran, such effects can be overcome through various recipemodifications. For example, the mixing process can be altered byincreasing the water added to the dough, such as by about two (2) to 10percent and/or increasing the mixing time until the gluten network isoptimized, as is understood by those skilled in the art. Alternately, orin addition, various additives, such as vital gluten, emulsifiers, andso forth, can be used to yield baked products similar in performance tothose manufactured with white wheat.

[0065] The bleached bran product of the present invention is anintermediate product that can be recombined with flours to produce anessentially “white” whole wheat flour having a fiber content comparableto conventional whole wheat flours, i.e., about 10 to 12%. Essentially,the white appearance and flavor identity of the resulting compositeflour is not altered by addition of the bleached bran. In oneembodiment, the flour is a “whole grain” flour, such that the fibercontent is at least about 5.5 g of dietary fiber per 100 g of flour. Thefat content of the composite flour can vary from about one (1) to three(3)%. However, the fat content can be adjusted, as needed, such as withthe addition of germ to the fiber. In one embodiment, the fat content ofthe composite flour is about two (2)%.

[0066] The flours can be of various types, such as bread flour (e.g.,from hard wheat), all-purpose flour used in a variety of baked goods,including breads, cakes, muffins, and so forth, pastry flour (softwheat) or durum flour. In one embodiment, the bran is recombined withdurum flour, to produce pasta. In this embodiment, the yellow color ofthe pasta, considered an attribute of quality, can also be increased, ifdesired, by blending it with semolina. Yellowing can also be controlledby temperature and pH, i.e., higher pH produces a more yellow product.

[0067] In one embodiment, the bran is sold as a bran ingredient, putinto dry mixes, added to ready-to-eat cereals, refrigerated uncooked orbakeable doughs, cooked cereal dough, and so forth. Use of bran inready-to-eat cereals increases the dietary fiber content and theantioxidant activity of the cereal. In one embodiment, the bran isadmixed with sugar, leavening agents (e.g., baking soda, baking powder,etc.) and salt. In another embodiment, the bran is combined with soy toproduce various soy products, such as meat-substitute products. In oneembodiment, the invention comprises any of the above named end products.

[0068] In one embodiment, the bran is sold as a bran ingredient, putinto dry mixes, added to ready-to-eat cereals, refrigerated uncooked orbakeable doughs, cooked cereal dough, and so forth. Use of bran inready-to-eat cereals increases the dietary fiber content and theantioxidant activity of the cereal. In one embodiment, the bran isadmixed with sugar, leavening agents (e.g., baking soda, baking powder,etc.) and salt. In another embodiment, the bran is combined with soy toproduce various soy products, such as meat-substitute products. In oneembodiment, the invention comprises any of the above named end products.

[0069] Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. This application isintended to cover any adaptations or variations of the invention. It isintended that this invention be limited only by the following claims,and the full scope of equivalents thereof.

What is claimed is:
 1. A method of bleaching bran, comprising: treatingbran with a hydrogen peroxide solution to produce lightened bran havingfewer native flavor components, the bran derived from a cereal grain. 2.The method of claim 1 wherein the hydrogen peroxide solution has a pH ofabout 6 to 7, further including adding an aqueous alkaline solution toraise the pH of the bran and hydrogen peroxide solution to about 9 to9.5 wherein the aqueous alkaline solution is added in amounts of about10 to 15 parts (dry weight) of alkaline material per 100 parts grain. 3.The method of claim 2 wherein the hydrogen peroxide solution is anaqueous solution having a concentration of between about 6 and 40%,further wherein the hydrogen peroxide is added in amounts of about 1 to20 parts of hydrogen peroxide to about 100 parts of bran.
 4. The methodof claim 3 wherein the hydrogen peroxide solution and alkaline solutionare heated together with the bran at a temperature of about 80 to 90° C.for about 20 to 60 minutes.
 5. The method of claim 3 wherein thehydrogen peroxide solution and alkaline solution are heated togetherwith the bran under a pressure of about 103.4 to 138 kPA (15 to 20 psi)and a temperature of about 120 to 130° C. for about one (1) to five (5)minutes.
 6. The method of claim 2 wherein the cereal grain is selectedfrom the group consisting of wheat, rice, barley, corn (maize), oats,triticale, amaranth, soybeans and mixtures thereof.
 7. The method ofclaim 6 wherein the cereal grain is red wheat or white wheat.
 8. Themethod of claim 7 wherein the cereal grain is a soft winter white wheatthat is milled to produce a light bran.
 9. The method of claim 1 whereinthe bran each have a particle size of at least about 100 microns. 10.The method of claim 1 further comprising: prior to bleaching, treatingthe bran with a chelating agent to remove transition metals to producetreated bran; and blanching the treated bran to inactivate catalase andperoxidase enzymatic systems to produce blanched bran.
 11. The method ofclaim 10 wherein the bran are treated with the chelating agent for aboutone (1) to 15 minutes at a temperature of about 70 to 90° C.
 12. Themethod of claim 10 wherein the chelating agent is selected from thegroup consisting of orthophosphate, metaphosphate, pyrophosphate,polyphosphate, calcium EDTA and sodium EDTA.
 13. The method of claim 12wherein the chelating agent is calcium EDTA or sodium EDTA in aconcentration of between about 0.02 and 0.1%.
 14. The method of claim 10wherein the blanching step is performed at a temperature of betweenabout 75 to 85° C. for about three (3) to ten (10) minutes, furtherwherein residual enzyme activity is below about 10 CIU/g bran followingthe blanching step.
 15. The method of claim 10 further comprising:washing and rinsing the bran to produce wet bran; filtering the wet branto produce filtered wet bran; treating the filtered wet bran withcatalase to remove residual hydrogen peroxide to produce treatedfiltered wet bran; and drying the treated filtered wet bran to producedried bleached bran having an L value on the Hunter scale of betweenabout 82 and
 93. 16. The method of claim 15 wherein there are at leasttwo washing and rinsing steps, each followed by a filtering step, priorto the bleaching step and at least one washing and rinsing step followedby at least one filtering step after the bleaching step.
 17. The methodof claim 15 wherein between about 0.1 and 0.4% of catalase, by weight,of bran is added to the filtered bran at a temperature of about 60° C.,further wherein the hydrogen peroxide concentration is reduced to lessthan about five (5) PPM following catalase treatment.
 18. A method forbleaching bran comprising treating wet bran with an oxidant in thepresence of heat, the oxidant selected from the group consisting ofhydrogen peroxide, ozone and peracetic acid.
 19. The method of claim 18wherein a combination of hydrogen peroxide and ozone bleaching is used.20. A method of bleaching cereal grains, comprising: treating bran with0.02 to 0.1% EDTA to produce treated bran; washing, rinsing andfiltering the treated bran to produce filtered and treated bran;blanching the filtered and treated bran at 75 to 85° C. for about three(3) to 10 minutes to produce blanched bran; washing, rinsing andfiltering the blanched bran to produce filtered and blanched bran;adding a one (1) to 10% alkaline solution and 30 to 35% hydrogenperoxide solution to the filtered and blanched bran at a temperature ofabout 80 to 85° C. for about 4 to 5 minutes to produce bleached bran;washing, rinsing and filtering the bleached bran to produce filtered andbleached bran; adding about 0.14 to 0.4% of catalase, obtain from afungi called Aspergillus nigers at a temperature of between about 55 to65° C. to the filtered and bleached bran to produce re-catalasedbleached bran; and drying the re-catalased bleached bran in a drum dryerto produce dried bleached bran having about five (5) to 13 g of waterper 100 g of dry bran and an L value of at least about
 75. 21. Ableached bran product suitable for admixing with whole wheat flour toproduce white whole wheat flour having an L value on the Hunter scale ofat least about
 82. 22. The product of claim 21 wherein about five (5)%bran, by weight, is added to the whole wheat flour.
 23. The product ofclaim 21 having an L value of between about 82 and
 93. 24. The productof claim 21 having a water absorption value about six times higher thannative bran.
 25. The product of claim 21 wherein native flavorcomponents are reduced or deactivated.
 26. The product of claim 21having an antioxidant activity about 15 to 35% higher than native bran.27. The product of claim 26 wherein the antioxidant activity isincreased due to increased availability of ferulic acid.
 28. A productprepared according to the process of claim
 1. 29. A product preparedaccording to the process of claim
 18. 30. A product prepared accordingto the process of claim
 20. 31. A whole wheat flour prepared fromperoxide-bleached bran, the whole wheat flour having an L value on theHunter scale of about and a dietary fiber content of about 10 to 12%.32. The whole wheat flour of claim 31 substantially free of hydrogenperoxide.
 33. The whole wheat flour of claim 32 prepared from soft whitewheat or hard white wheat.
 34. The whole wheat flour of claim 33prepared from light bran.
 35. The whole wheat flour of claim 33 having apH of about 6.3 to 6.7.
 36. A finished baked good prepared from thewhole wheat flour of claim
 31. 37. The whole wheat flour of claim 31admixed with sugar, salt, and leavening.
 38. A bleached bran productsuitable for use as an additive in foods.
 39. The bleached bran productof claim 37 wherein the product is added to foods selected from thegroup consisting of dry mixes, ready-to-eat cereals and soy.
 40. Arefrigerated uncooked or bakeable dough product comprising bleachedbran.
 41. A ready-to-eat cereal comprising bleached bran.
 42. A cookedcereal dough comprising bleached bran.